1. Field of Invention
This invention relates to the heat treatment of unchlorinated flour to make a substitute for chlorinated cake flour.
2. Description of Prior Art
In the United States, cake flour is used in a wide variety of food products. A substantial amount of it is used in making "high ratio" layer cakes. In these cakes, the ratio of sugar to flour is in the order of 1.25 to 1.30. Such high amounts of sugar give cake desirable attributes such as flavor, moistness, lightness, texture and tenderness.
Notwithstanding the acceptance of chlorinated flour in the U.S., chemical treatments and chemical food additives have become suspect and it is desirable to avoid such treatments whenever possible. In addition, most foreign countries prohibit the use of chlorinated cake flour. As a result, those countries do not allow importation of American dry mix products.
Many attempts have been made to develop a substitute for chlorinated flour and a method for preparing such flour. To date, the use of chlorinated cake flour is still widespread and no substitute or method therefor has yet been developed.
Most of the described flour treatments have not been adopted for two primary reasons: First and foremost is the cost. Second is their performance, i.e., the taught methods do not work very well.
Most of the proposed processes have included the heat treatment of unchlorinated flour, or the wheat from which it is made, to improve its baking properties.
For the present purpose, a general review of the heat treatment of flour was made.
The conversion of bread flour to cake flour, by heating for about 1 min. to 17 hrs. at temperatures ranging from 150 to 360.degree. F., is claimed in U.S. Pat. No. 3,428,461, by W. A. Hatton et al. Preferred conditions are 1 hr. at 180.degree. F., in a tray stored in a laboratory convection oven, or 1 hr. at 210.degree. F. in a pressurized blender. Both methods permit extensive exposure of hot flour to air.
In U.S. Pat. No. 3,490,917 by Doe and Russo, either a starch or a flour obtained by air classification of wheat flour is heated 30 mins. at 100 to 120.degree. C. The process is carried out in a screw conveyer equipped with a steam jacket. The inventors stress the need for conditions which permit water vapor to escape. The flour is spread on trays to cool. The recipe in which the flour is used requires additional egg white, in order to equal the baking properties of the chlorinated flour standard.
U.S. Pat. No. 3,974,298, by Cauvain et al., discloses a process for heating wheat 30 mins. at 120.degree. C., or by heating semolina 1 hr. at 100.degree. C., to improve the quality of flour produced by milling. Heat treatment is effected in trays in a laboratory oven, in which there is extensive contact of hot flour and air.
In U.S. Pat. No. 4,157,406 by Hanamoto et al., a laboratory method for cake flour discloses that either unchlorinated flour, that has been heated 1 hr. to 2 wks. at 49 to 93.degree. C., or starch, which has been subjected to swelling, can be substituted for chlorinated flour in high ratio cakes.
In U.S. Pat. No. 4,259,362 also by Hanamoto et al., hard wheat normally used for making bread flour is simultaneously ground and heated. Then it is air classified to obtain a flour suitable for high ratio cakes.
U.S. Pat. No. 5,389,388, by Gusek, discloses a process wherein unchlorinated flour is heated 1 to 2 mins. in a microwave oven at 230 to 270.degree. F. The so-heated flour, when included in dry mixes containing 15% of the emulsifier glycerol monostearate, has baking properties as good as the chlorinated standard. In this process, the considerable contact of hot flour and air is disregarded.
However in U.S. Pat. No 5,395,639, by Chawan et al., the inventors recognize the deleterious effect of exposure of flour to air and devise the following ways to minimize such contact: 1. Coarse grinding reduces the area of the flour; 2. Dough is made immediately after milling; 3. The grinder and the mixer are flushed with nitrogen during those operations.
Since oxidative degradation occurs whenever hot flour is exposed to air, all the taught methods for heat treatment of flour produce unknown amounts of oxidative degradation by-products. These substances adversely affect the baking properties of heat treated flour, HTF and the eating qualities of the cakes derived therefrom.